Write balanced chemical equations for the following statements:

(i) $\text{NaOH}$ solution is heated with zinc granules.

(ii) Excess of carbon dioxide gas is passed through lime water.

(iii) Dilute sulphuric acid reacts with sodium carbonate.

(iv) Egg shells are dropped in hydrochloric acid.

(v) Copper (II) oxide reacts with dilute hydrochloric acid.

The balanced chemical equations for the given statements are:

(i) $NaOH$ solution is heated with zinc granules:

$$2NaOH(aq) + Zn(s) \xrightarrow{\Delta} Na_2ZnO_2(aq) + H_2(g)$$

(Product: Sodium zincate and Hydrogen gas)

(ii) Excess of carbon dioxide gas is passed through lime water:

First, lime water turns milky due to the formation of insoluble calcium carbonate:

$$Ca(OH)_2(aq) + CO_2(g) \rightarrow CaCO_3(s) + H_2O(l)$$

On passing excess carbon dioxide, the milkiness disappears due to the formation of soluble calcium hydrogencarbonate:

$$CaCO_3(s) + H_2O(l) + CO_2(g) \rightarrow Ca(HCO_3)_2(aq)$$

(iii) Dilute sulphuric acid reacts with sodium carbonate:

$$Na_2CO_3(s) + H_2SO_4(aq) \rightarrow Na_2SO_4(aq) + H_2O(l) + CO_2(g)$$

(iv) Egg shells are dropped in hydrochloric acid:

Egg shells are made of calcium carbonate ($CaCO_3$). The reaction is:

$$CaCO_3(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + H_2O(l) + CO_2(g)$$

(v) Copper (II) oxide reacts with dilute hydrochloric acid:

$$CuO(s) + 2HCl(aq) \rightarrow CuCl_2(aq) + H_2O(l)$$

(Product: Copper (II) chloride, which gives a blue-green colour to the solution)